When one wishes to assemble a glass on a case, in particular for edge-to-edge assembly, i.e. without any slot for the glass, and particularly when the case is made at least partially of ceramic material in order to obtain the broadest possible palette of colours, the usual technique consists in metallizing the inner part of the glass in the zone where one wishes to form the joint, depositing a line of adhesive on the corresponding part of the case, then assembling the glass by pressure. The purpose of the metallizing is primarily to conceal the line of adhesive, which may have, from the start, a more or less regular contour, making it visible to the naked eye. Metallizing also enables the aging phenomena of the adhesive joint, such as shrinkage or yellowing, to be concealed. The method basically consists in depositing a primer layer, for example chromium, then by evaporating various metals (Cr, Ti, Pd, Au, . . . ) or alloys to obtain a large enough palette of shades that will all have a metallic hue. Metallizing cannot provide matte non-metallic hues, or white, which has the drawback of limiting the choice of hues for the case or its external parts.
This drawback is particularly important for cases including ceramic elements that can be manufactured in an infinite range of shades and hues but for which it is not always possible to find aesthetically appropriate metallizing.